1. Field of the Invention
The invention relates to a method for controlling the operation of an automatic clothes washer.
2. Description of the Related Art
Automatic clothes washers are ubiquitous. Such appliances clean fabric items effectively, enabling the homeowner to complete other tasks or engage in more satisfying activities while doing the laundry. Modem clothes washers provide a multitude of options for matching a selected cleaning operation to the type of fabric comprising the laundry load and the degree of soiling of the laundry load.
In a conventional automatic clothes washer, cleaning of the fabric items is primarily attributable to three factors: chemical energy, thermal energy, and mechanical energy. These three factors can be varied within the limits of a particular automatic clothes washer to obtain the desired degree of cleaning.
The chemical energy is related to the types of wash aids, e.g. detergent and bleach, applied to the fabric items. All other things being equal, the more wash aid that is used, the greater will be the cleaning effect.
The thermal energy relates to the temperature of the fabric items. The temperature of the wash liquid typically is the source of the thermal energy. However, other heating sources can be used. For example, it is known to use steam to heat the fabric items. All things being equal, the greater the thermal energy, the greater will be the cleaning effect.
The mechanical energy is attributable to the contact between the clothes mover and the fabric items, the contact between the fabric items themselves, and the passing of the washing liquid through the fabric items. In washing machines with a fabric mover, the fabric mover tends to cause the fabric items to contact themselves, and for the wash liquid to pass through the fabric items. All things being equal, the greater the amount of mechanical energy, the greater will be the cleaning effect. The longer the time during which the fabric items contact the clothes mover and other fabric items, the greater the amount of mechanical energy delivered to the laundry load.
It has not yet been possible to determine the amount of mechanical energy imparted to a particular wash load. Typically, the mechanical energy imparted to a load is estimated based on empirically determined data from a development laboratory that is then stored within the controller for utilization in clothes washers in use in customer homes. The empirical data is normally determined for pre-determined operation conditions such as: load weight, fabric type, and liquid level. However, not every possible combination is tested and stored in the machine as it is impractical. Nor is it possible to do so because the actions of the user cannot be anticipated. For example, a user might mix fabric types, say, normal and delicate, and then pick a delicate wash cycle. Therefore, the empirical data is, to some degree, a best guess of the mechanical energy imparted to the clothes load.
The use of empirical data can lead to either too much or too little mechanical energy being imparted to the clothes load. Too little mechanical energy will typically mean that the clothes load is not cleaned to the desired standard, particularly for certain soils which require mechanical force to be removed. Too much mechanical energy will get the clothes cleaned to the desired standard, but it wastes resources (extra energy consumption) in doing so and adds additional wear or fabric damage to the fabric items.
It would be advantageous to the overall cleaning performance if the mechanical energy imparted to the fabric items could be determined during the washing process.